Why Does an Aluminum Ring Levitate Above a Magnetic Coil?

[cheez]

A magnetic coil connected to AC power and an aluminum ring. The ring was placed on top of the coil and, although aluminum is non magnetic, the ring was thrown to the ceiling. Explain 1, why was there any force on the ring? 2. Why the ring went up? Use diagram and Faraday's Law

I don't know how to answer these questions. :(
I know the alternating current makes the magnetic field changes. And the changing magnetic field generates emf.But I don't know why the emf is large enough to push the aluminum ring upward, and how come it goes up?

thx a lot.

 

[Tide]

A few more details might help but I would examine the Lorentz force acting on the electrons that were set in motion by the induced EMF.